Pregnancy outcome in in vitro fertilization decreases to a plateau with repeated cycles.

Clinical pregnancy rate (CPR) and implantation rate (IR) in 1,177 patients who had 1,788 fresh, nondonor, nonPGD IVF cycles were highest in cycle 1, significantly declined in cycle 2, and reached a plateau for cycles 3-5 at a rate lower than in cycle 2. In patients >38 years of age CPR and IR in cycles 1 and 2 were significantly lower than in younger patients, but there was no decline in CPR or IR with advancing IVF attempts.